Scientists determine cause behind huge Asian smoke cloud

Scientists determine the cause behind huge Asian smoke cloud

New research published recently in Proceedings of the National Academy of Sciences presents surprising findings concerning the origins of the smoke cloud that hung over Southeast Asia for several months in 2015. The smoke, which came from wildfires that spread throughout Indonesia in 2016 due to a severe El Nino-driven drought, stayed clouding the region throughout the summer and fall of 2015. Scientists have now determined that the smoke contained carbon from plants that were alive during the Middle Ages, as a result of the burning of ancient peat.

“Our research shows that almost all of the smoke emissions originated from the burning of Holocene-aged peat,” said first author Elizabeth Wiggins, a postdoctoral research fellow at NASA’s Langley Research Center. “Although this peat has functioned as a massive terrestrial carbon storage reservoir over the last several thousand years, it is now a significant source of carbon to the atmosphere.”

The researchers were able to determine the origin of the smoke through isotope dating of smoke particles’ carbon atoms. After determining that the average particle was as old as 800 years, the scientists cross-analyzed the data with models of the wind-driven movement of smoke plumes and were able to pinpoint that the smoke came from burning peat on Borneo and Sumatra of Indonesia.

“These are the first direct measurements showing the smoke originated from the combustion of peat layers that are hundreds to thousands of years old,” said study co-author James Randerson. “Farmers drain the peats because waterlogged soils are bad for growing oil palms and other crops, and they seek to burn off surface layers to get to the mineral soil below.”

Peatlands are some of the most effective carbon sinks, holding more carbon all of the living biomass of the Amazon rainforest. The release of this huge amount of carbon into the atmosphere has grim consequences for the world as a whole, not just the orangutans and Sumatran tigers that lost their habitat.

The authors want to drive home one specific point from their findings: “This was all human-driven,” Randerson said. “Such fires help a small part of the population, but the costs for people far away in other cities in the region are enormous.” In order to preserve peatlands and thus keep huge quantities of carbon out of the atmosphere, we must find another way to pursue agriculture. Burning is no longer an option. “We need to identify more sustainable agricultural solutions in which we preserve tropical forests and peatlands to maintain all of these benefits while at the same time enhancing food security,” co-author Claudia Czimczik said.